The present application is based on and claims priority from Japanese Patent Application 2000-97906 filed Mar. 30, 2000, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an indicating instrument for various devices, and particularly, a vehicular indicating instrument having a luminous pointer.
2. Description of the Related Art
In a vehicular indicating instrument having a luminous pointer, a main portion of a drive unit is disposed behind a dial plate, and a rotary shaft extends outward from a through hole of the dial plate to carry a pointer at the end thereof. A pointer-illumination light emitting diode is disposed near the rotary shaft and the through hole behind the dial plate. A dial-plate-illumination light emitting diode may be also disposed near the rotary shaft behind the dial plate. Generally, such light emitting diodes are not sufficiently resistant to heat of soldering and a heat shock, if repeated.
If a step motor, which usually employs a resinous speed reduction gear train, is installed in the drive unit, it should be taken into account that such a step motor may not be resistant to the heat of soldering or heat shocks very much.
A main object of the invention is to provide an improved and reliable indicating instrument that includes a light emitting diode and other heat-sensitive parts.
According to a main feature of the invention in an indicating instrument that includes a transparent dial plate, a printed circuit board disposed behind the dial plate, a drive unit and a light conductive luminous pointer and a light emitting diode, a plurality of lead wires extended from the drive unit is respectively soldered to such distant portions on the printed circuit board from the diode that can insulate the diode from soldering heat.
Although the heat of soldering the light emitting diode to the circuit board is high and heat stresses are applied to the light emitting diode, the light emitting diode is not damaged because such heat and stress are the first heat to be applied to the diode and not applied thereto any more.